Current small or compact utility tractors are used for mowing, as well as for doing utility work such as rotary hoeing, plowing and cultivating small areas of ground. Often, this requires a mower deck to be mounted on the central portion of the tractor and additional implements to be mounted on a typical 3-point hitch extending from the rear of the tractor. Since these tractors are relatively small, it is necessary to utilize single power units, such as a hydraulic cylinder, to do many of the jobs in raising and lowering the implements. For example, it may be desirable to provide a small front-mounted loader on the utility tractor that utilizes hydraulic cylinders to raise and lower the loader arms. Generally, therefore, it may be desirable to provide lift systems on the front, central and rear portions of the tractor with a very minimum number of hydraulic cylinders for operating the lift systems.
Often, for example, it is desired to use the power unit or hydraulic system that operates the linkages in the rear-mounted 3-point hitch to raise and lower a centrally mounted mower deck. Also, while a mower deck is mounted on the central portion of the tractor, it may be desirable to mount and use a loader extending from the forward end of the tractor. Often, due to limited hydraulic capacity on the small tractor, it will be necessary to use cylinders using the same hydraulic circuit for operating the lift mechanism for the centrally mounted mower and the loader arms.
Typically, to accomplish some of the above, there is provided on the tractor a cable or linkage connection between the lower draft links of the 3-point hitch and the lift mechanism for raising and lowering the mower deck. In this manner, the single hydraulic cylinder which is utilized to operate the draft links may also be used to raise and lower the mower deck. This creates no problem when there is no rear-mounted implement and it is only desired to raise and lower the mower deck. Likewise, if there is no mower deck on the mid-portion of the tractor, an implement mounted on the 3-point hitch creates no problem. The problem exists when it is desired to retain a mower deck on the tractor while using an implement mounted on the 3-point hitch. The mower and implement will be raised and lowered in unison which often is not desired. In many instances, it is desirable to retain the mower deck in an uppermost or transport position while using a piece of equipment of the 3-point hitch.
In order to alleviate this condition, it is typical to move the connecting cable or linkages outboard of the tractor housing or frame so that access can be made to the linkage or cable for purposes of locking the mower in its uppermost position. The appearance of a utility tractor affects the sales potential of the tractor, i.e., a clean-looking, uncluttered tractor has more sales appeal than one that has exposed cables and linkages. Also, it is desired to cover the cable and linkages so as to protect them against injury or damage from the elements.
It is often desirable to operate only the rear 3-point linkage for raising or lowering an implement thereon and to hold the mower deck in a raised or inoperative position. To do this, it is necessary for the tractor operator to, in some manner, disconnect the linkage or cable that extends from the lower lift system of the rear of the tractor from the rockshaft that operates to raise or lower the mower deck. It is also necessary, in some manner, to hold the deck in a raised position. To do this, the operator must get off the tractor and physically attach transport latches on the lift system or between the tractor frame and mower deck. Similarly, if a mower deck is supported on the tractor at the same time a front mounted loader is supported on the front end of the tractor and the power lift systems are interconnected, a similar operation of holding or latching the mower deck in a raised position must be done.
On tractors having the capacility of using a single hydraulic circuit for moving a central mower deck or other type of implement to a desired vertical position, the hydraulic system is often used to retain or lock the implement in that position. Such hydraulic systems often are controlled by a lever that may be moved to different positions having visual readings alongside that indicates the height of the implement. The problems that are inherent in such systems are twofold. First, there are leakages in hydraulic systems so that in day-to-day operation, movement of the lever to a desired position does not always give the same height position of the implement. Often, if leakage is severe enough, the height position of the implement will vary in the same period of operation. Second, the weight of the mower or implement is carried continuously and totally by the hydraulic system and such is not considered desirable design practice since it may cause premature leakage or other failure of the system.
With the above in mind, it is a primary object of the present invention to provide a rockshaft and lift arms thereon for raising and lowering the deck on the central portion of the tractor. The rockshaft is interconnected to a power source, whose primary purpose is to raise and lower the trailing links of the 3-point linkage on the rear of the tractor. This is done through a linkage that extends lengthwise of the tractor and in a frame channel that extends normally in a fore-and-aft disposition on the tractor. The linkage has a lost motion connection therein whereby the power means can operate the rearwardly extending links through a range that does not affect the corresponding range of rocking action of the transverse rockshaft. Provided on the floor of the tractor, which is the overhead wall structure of the channel, is a locking device in the form of an extendible and retractable link that is controlled on the floor by a swivel action. As the extendable and retractable linkage is extended through the swivel action, the rockshaft will be locked to hold the mower deck in a raised or desired grass cutting position. It should be understood that the locking device is not meant, in any manner, to affect raising and lowering of the mower deck, but only serves the purpose of locking the mower deck in a raised or desired grass mowing height after the power unit is used to force the deck into that position.
It is also the purpose of the present invention to provide a unique locking system that is composed of a swivel member extending through the floor or overhead panel of the tractor frame channel with a portion projecting above the floor and a portion projecting beneath the floor. The swivel member is freely swivable on the floor but is fixed against the vertical movement with respect thereto. The lower end of the swivel member is hollow and has an internal hexagonal axial opening. Fixed against rotation on the channel wall structure is a pipe-like member disposed beneath and generally as a downward continuation of the swivel member. This member has an internal threaded portion. A threaded stud with an hexagonal head fitting into the open bottom end of the swivel member is threadedly mounted in the threaded portion. As the swivel member is rotated, the stud is adjusted vertically in the threaded internal portion of the pipe-like member. A vertical connecting rod is connected to the rockshaft in a radial offset position with respect to its axis and has its upper end extending into the lower end of the pipe-like member so as to contact the lower end of the stud. As the swivel member is rotated, it affects the vertical movement of the rod and a corresponding rocking of the rockshaft. Upon the power means rotating the rockshaft so as to position the corresponding implement or mower deck, the swivel may be operated to engage the rod and to thereby hold the mower in its desired position. The load of the mower deck is thereby transferred from the hydraulic system to the rod, stud and eventually to the frame channel of the tractor. Also, until the swivel member is moved from its locked position, the mower deck will always return to the same height even if the hydraulic system temporarily raises it. The lost motion in the linkage extending from the power means to the rockshaft will permit the power means to be used to operate other structure and equipment upon the tractor. In a modification of the invention, a similar arrangement is made for locking the mower in an up or transport position so that the hydraulic power may be used exclusively for operating front mounted implements.